The invention relates to packet routing via an infrastructure where an end-to-end cyclical redundancy check (ECRC) is used.
In systems where a packet is provided with an ECRC, this can be used at intermediate points throughout an infrastructure as well as at an end point for checking the integrity of the packet. The ECRC should not, however, be modified at the intermediate points as this could lead to corruption of the ECRC if, for example, checking and modifying the ECRC at an intermediate node were faulty.
Where a common protocol is used over the infrastructure, this does not normally cause any problems. However, difficulties can occur in a situation where an infrastructure is shared between multiple protocols and/or a modified protocol may be used, particularly if it is intended to be transparent to the infrastructure that it is being shared and/or a different or modified protocol is being used. An example may be where modifications to a packet, for example to provide changes to routing and/or address mappings, are required after the ECRC had been applied to the packet.
The invention seeks to mitigate these problems.